Mitt Romney's good week just got better with a coveted endorsement from former Florida governor Jeb Bush.

The brother and son of former presidents George W. Bush and George H.W. Bush said that now is the time for Republican voters to "to unite behind Governor Romney and take our message of fiscal conservatism and job creation to all voters this fall."

This week, Romney has won primary elections in both Puerto Rico[3] and Illinois[4], expanding his lead over Rick Santorum by 60 delegates and putting him 300 delegates ahead of the former Senator. Romney has now amassed a total of 563 delegates out of the 1,144 needed to clinch the Republican nomination and take on President Obama in November's general election.

Jeb Bush, who spent eight years as the governor of Florida, from 1998 to 2006, is a Republican heavyweight whom many assumed would enter the nomination race. His father, former President George H.W. Bush, also endorsed Romney in December.

Romney has the most endorsements in the race from elected officials, including former governors Tim Pawlenty and Jon Huntsman, both of whom dropped out of the nomination fight. He also boasts an endorsement from New Jersey governor Chris Christie, whom many Republicans also hoped would throw his hat in the ring.

Fellow wannabe nominees Santorum, Newt Gingrich and Ron Paul have, however, vowed to stay in the race, with Gingrich's spokesman, R.C. Hammond, reportedly stating that Bush's endorsement is merely the "the completion of the establishment trifecta", in reference to Bush's father and former Senate Majority Leader Bob Dole.